Install wakeboard tower on 230 se

Has anyone installed an aftermarket tower on a 230se. Recently purchase a fly high pro x series tower just waiting for it to arrive. I have figure out how to remove seat backs in the bow to access front support locations however not sure how to remove and access the rear mount area of the tower. This tower can span 48 - 70" from front support to rear support. At the rear support area there are bumper cushions on side of gunnel not sure how to remove. Is this the location to drill large access hole?